An example of a configuration of an LM (Light Matrix) type optical-sensor touch panel is schematically shown in FIGS. 1 and 2. FIG. 1 is a front view showing an LM-type optical-sensor touch panel, and FIG. 2 is a cross sectional view of the LM-type optical-sensor touch panel shown in FIG. 1, taken along line A-A of FIG. 1.
As shown in FIG. 1, mirrors 2 are arranged at upper, left, and right edges of a display surface of a liquid crystal panel 1. A plurality of mirrors 2 need to be arranged at each of the upper, left, and right edges for lower implementation cost. In addition, as shown in FIG. 1, a plurality of LEDs are arranged at a lower edge of the display surface of the liquid crystal panel 1 as an LED (Light Emitting Diode) 3.
The liquid crystal panel 1 has optical sensors 4 embedded therein at positions immediately under the mirrors 2 (see FIG. 2), such that a plurality of optical sensors 4 are arranged at each of the upper, left, and right edges.
Light emitted from the LED 3 spreads out to cover a surface of the liquid crystal panel 1 (see FIG. 1). The light that has spread over the surface of the liquid crystal panel 1 is directed by the mirrors 2 to the optical sensors 4 (see FIG. 2). The LM-type optical-sensor touch panel shown in FIGS. 1 and 2 includes a data processing section (not shown), and input positions on which input operations are performed by using, for example, a pen point or a fingertip is detected through processing of outputs from the optical sensors 4 performed by the data processing section.